Primeras descripciones de agregaciones pelágicas diurnas de langostino (Pleoticus muelleri) utilizando una ecosonda de banda ancha operando frecuencias múltiples

This is the first description of diurnal pelagic aggregations of the bottom-dwelling Argentine red shrimp (Pleoticus muelleri) registered with a broadband scientific echosounder. A pelagic trawl net and an underwater video camera were used to validate all the information presented in this paper. Shrimp aggregations were characterized by increasing frequency response, more evident at frequencies greater than 120 kHz. Identification of the acoustic signature of this resource is of particular interest for the development of new methodologies to complement the traditional swept area method of estimation.Reportamos la primera descripción de agregaciones pelágicas diurnas de langostino (Pleoticus muelleri) utilizando una ecosonda científica de banda ancha. Toda la información presentada en este manuscrito fue validada por medio de una red de arrastre pelágica y una cámara de video submarina. Las agregaciones de langostino se caracterizaron por poseer una respuesta en frecuencia creciente, siendo más evidente a frecuencias superiores a 120 kHz. La identificación de la firma acústica de las agregaciones pelágicas de langostino es de particular interés para el desarrollo de nuevas metodologías que complementen la evaluación tradicional de este recurso, realizada a través del método por área de barrida

Spectral shapes of solid neon

We present a Path Integral Monte Carlo calculation of the first three moments of the displacement-displacement correlation functions of solid neon at different temperatures for longitudinal and transverse phonon modes. The Lennard-Jones potential is considered. The relevance of the quantum effects on the frequency position of the peak and principally on the line-width of the spectral shape is clearly pointed out. The spectrum is reconstructed via a continued fraction expansion; the approximations introduced using the effective potential quantum molecular dynamics are discussed.Comment: 3 pages, 2 figures, 3 table

Immunization With Bovine Herpesvirus-4-Based Vector Delivering PPRV-H Protein Protects Sheep From PPRV Challenge

The Morbillivirus peste des petits ruminants virus (PPRV) is the causal agent of a highly contagious disease that mostly affects sheep and goats and produces considerable losses in developing countries. Current PPRV control strategies rely on live-attenuated vaccines, which are not ideal, as they cannot differentiate infected from vaccinated animals (DIVA). Recombinant vector-based vaccines expressing viral subunits can provide an alternative to conventional vaccines, as they can be easily paired with DIVA diagnostic tools. In the present work, we used the bovine herpesvirus-4-based vector (BoHV-4-A) to deliver PPRV hemagglutinin H antigen (BoHV-4-A-PPRV-H-ΔTK). Vaccination with BoHV-4-A-PPRV-H-ΔTK protected sheep from virulent PPRV challenge and prevented virus shedding. Protection correlated with anti-PPRV IgGs, neutralizing antibodies and IFN-γ-producing cells induced by the vaccine. Detection of antibodies exclusively against H-PPRV in animal sera and not against other PPRV viral proteins such as F or N could serve as a DIVA diagnostic test when using BoHV-4-A-PPRV-H-ΔTK as vaccine. Our data indicate that BoHV-4-A-PPRV-H-ΔTK could be a promising new approach for PPRV eradication programs

Spawning and fecundity of the white croaker Micropogonias furnieri Desma rest, 1823 of the Rio de la Plata estuary, Argentina

Se estima la fecundidad parcial y relativa de la corvina rubia Micropogonias furnieri Desmarest, 1823 del Río de la Plata, se calcula su frecuencia reproductiva y se analizan los movimientos de los grupos desovantes durante la reproducción. El estudio se realizó en la zona común de pesca argentino-uruguaya (Atlántico sudoccidental, 34°-39° 30'S) durante el mes de noviembre. Se utilizaron 373 hembras para el análisis histológico de los ovarios, de las que se seleccionaron 31 ejemplares en estadio de hidratación ovocitaria para la determinación de la fecundidad a partir del conteo de ovoritos hidratados por el método gravimétrico. La frecuencia reproductiva se estimó calculando el porcentaje de hembras con folículos postovulatorios en las muestras. El desove de la corvina rubia se concentra en el sector interno del estuario del Río de la Plata en coincidencia con el frente salino de fondo. En el resto del estuario las hembras se encuentran activas, en fase de recuperación gonadal, desplazándose posteriormente hacia el sector interno, donde completan la maduración y desovan. La frecuencia reproductiva promedio fue de 12 días; la fecundidad parcial varió entre 50 000 y 750 000 ovocitos para un rango de tallas entre 31 cm y 62 cm de longitud total, observándose un ajuste de tipo potencial en relación con la longitud total y un ajuste lineal en relación con el peso total (libre de ovamos). La fecundidad relativa presentó un valor promedio de 232 ovocitos por gramo de hembra (libre de ovarios), encontrándose una relación positiva con la talla de los ejemplares.Relative fecundity, batch fecundity and spawning frequency of white croaker Micropogonias furnieri Desmarest, 1823 of the Rio de la Plata estuary were estimated. Displacements of the spawning groups during the reproductive season were also analysed. The study was carried out in the Argentine-Uruguayan Common Fishing Zone (South-west Atlantic, 34°-39° 3O'S), during November For the histological analysis of ovaries, 373 females were sampled. Thirty-one individuals with hydrated ovaries were selected for the fecundity estimates. The number of hydrated oocytes was determined with the gravimetric method, and the spawning frequency was estimated from the daily proportion of females with postovulatory follicles. Micropogonias furnieri spawns in the inner zone of the Rio de la Plata estuary, in coincidence with the bottom saline front. In the rest of the estuary, the individuals remain in the partially spent stage, moving afterwards to the inner sector where they reach maturity, and spawn. Mean spawning frequency was 12 days, and batch fecundity ranged between 50000 to 750 000 oocytes for females between 31-62 cm, total length. The relationship of batch fecundity vs total length presented a better fit to the potential model, while the regression batch fecundity vs total weight (ovary-free) was lineal. The mean relative fecundity was 232 oocytes per female gram (ovary-free), showing a positive relationship with total length.Instituto Español de Oceanografí

Geometric dynamical observables in rare gas crystals

We present a detailed description of how a differential geometric approach to Hamiltonian dynamics can be used for determining the existence of a crossover between different dynamical regimes in a realistic system, a model of a rare gas solid. Such a geometric approach allows to locate the energy threshold between weakly and strongly chaotic regimes, and to estimate the largest Lyapunov exponent. We show how standard mehods of classical statistical mechanics, i.e. Monte Carlo simulations, can be used for our computational purposes. Finally we consider a Lennard Jones crystal modeling solid Xenon. The value of the energy threshold turns out to be in excellent agreement with the numerical estimate based on the crossover between slow and fast relaxation to equilibrium obtained in a previous work by molecular dynamics simulations.Comment: RevTeX, 19 pages, 6 PostScript figures, submitted to Phys. Rev.

Conditional Intensity and Gibbsianness of Determinantal Point Processes

The Papangelou intensities of determinantal (or fermion) point processes are investigated. These exhibit a monotonicity property expressing the repulsive nature of the interaction, and satisfy a bound implying stochastic domination by a Poisson point process. We also show that determinantal point processes satisfy the so-called condition $(\Sigma_{\lambda})$ which is a general form of Gibbsianness. Under a continuity assumption, the Gibbsian conditional probabilities can be identified explicitly.Comment: revised and extende

C60_{60} in intense femtosecond laser pulses: nonlinear dipole response and ionization

We study the interaction of strong femtosecond laser pulses with the C$_{60}$ molecule employing time-dependent density functional theory with the ionic background treated in a jellium approximation. The laser intensities considered are below the threshold of strong fragmentation but too high for perturbative treatments such as linear response. The nonlinear response of the model to excitations by short pulses of frequencies up to 45eV is presented and analyzed with the help of Kohn-Sham orbital resolved dipole spectra. In femtosecond laser pulses of 800nm wavelength ionization is found to occur multiphoton-like rather than via excitation of a ``giant'' resonance.Comment: 14 pages, including 1 table, 5 figure

Consumo de Savia por Melanerpes cactorum y su Rol en la Estructuración de Ensambles de Aves en Bosques Secos

The White-fronted Woodpecker (Melanerpes cactorum) drills holes in branches and trunks to feed on sap flows, providing an energy-rich food resource for other birds. Here we describe ecological and behavioral traits of the White-fronted Woodpecker related to its sap-feeding habits in the semiarid Chaco of Argentina and explore the structure of the avian assemblage in relation to the sap resource. Sap consumption by the White-fronted Woodpecker and other sap-feeding species was strongly seasonal and positively associated with periods of resource scarcity. The White-fronted Woodpecker actively defended the sap wells from smaller birds. Specialist and facultative nectarivores that assimilate sucrose at a high rate represented an important proportion of sap-feeding birds. In this system of woodpecker, sap, and other sap-feeding species, each species’ consumption depends on its physiological and behavioral characteristics as well as on the availability of other food in the surrounding environment.Melanerpes cactorum perfora ramas y troncos de árboles y arbustos para consumir la savia que fluye de las perforaciones, posibilitando a otras especies de aves el acceso a un recurso de alto contenido energé- tico. En este estudio describimos rasgos de la historia natural de M. cactorum relacionados con su alimentación en el Chaco semiárido de Argentina e investigamos la estructuración de ensambles de aves en torno al recurso savia. Para M. cactorum y las especies de aves que consumieron savia, el consumo de savia fue marcadamente estacional, posiblemente asociado a periodos de escasez de recursos. Melanerpes cactorum defendió activamente las perforaciones ante algunas especies de aves cuya masa corporal fue menor a la de los carpinteros. Las especies nectarívoras especialistas y facultativas con alta tasa de asimilación de sacarosa representaron una importante proporción de las aves que consumieron savia. En el sistema carpinteros–savia–aves consumidoras de savia, el consumo de este recurso depende de características fisiológicas y comportamentales de las especies, como así también de la disponibilidad de otros recursos alimenticios en los ambientes que habitan.Fil: Nuñez Montellano, Maria Gabriela. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; ArgentinaFil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; ArgentinaFil: Macchi, Leandro. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentin

Kinetic energy of solid neon by Monte Carlo with improved Trotter- and finite-size extrapolation

The kinetic energy of solid neon is calculated by a path-integral Monte Carlo approach with a refined Trotter- and finite-size extrapolation. These accurate data present significant quantum effects up to temperature T=20 K. They confirm previous simulations and are consistent with recent experiments.Comment: Text and figures revised for minor corrections (4 pages, 3 figures included by psfig